1. Field of the Invention
The present invention relates to a silicon thin film anode for a lithium secondary battery and a preparation method thereof, and more particularly, to a silicon thin film anode for a lithium secondary battery having enhanced cycle characteristics and capacity and a preparation method thereof.
2. Description of the Background Art
Among secondary batteries, a lithium battery is being most spotlighted due to its high energy density and light weight. Especially, a lithium secondary battery is being mainly used in portable electronic appliances such as a mobile phone and a notebook. As IT technologies are continuously developed domestically or in foreign countries, demands for the lithium secondary battery in the future are expected to drastically increase. Under this situation, domestic electronic companies are researching to increase productivity for the lithium secondary battery every year.
The lithium secondary battery includes a silicon thin film anode. In order to enhance cycle characteristics and capacity, the conventional silicon thin film anode was prepared by a structure of an Si—Ag multi-layer that a silicon (Si) layer and a silver (Ag) layer are repeatedly laminated, disclosed in Korean Patent Application No. 10-2001-0052112, a structure that a silicon-metal (Si-M) layer and a silver (Ag) layer are repeatedly laminated, disclosed in Korean patent Application No. 10-2001-0051588, and a structure that a silicon (Si) layer and a molybdenum (Mb) layer are alternately laminated, disclosed in Korean Patent Application No. 10-2006-0067459.
However, the conventional structures and preparation methods are complicated. Furthermore, when a lithium secondary battery is continuously charged and discharged, a structure variation easily occurs due to a volume change of a silicon layer. The structure variation causes a silicon layer to be separated from a collector, thereby gradually decreasing a capacity and a cycle performance of the lithium secondary battery.